Did the oceans cool during the Eocene-Oligocene greenhouse to icehouse transition?

One of the most important climatic events in Earth history happened about 34 million years ago at the close of the Eocene epoch, when a thick ice sheet grew in East Antarctica for the first time. We do not know what triggered this dramatic change, but there are two main ideas. One is that Antarctic temperatures decreased until snow remained frozen all year round, forming an ice cap. Such a cooling could have been caused by decreasing atmospheric concentrations of greenhouse gases. Alternatively, Antarctica may already have been cold enough, but a change in ocean currents made the Antarctic weather wetter. This could have provided the moisture necessary to form snow and ice.

This project aims to test these ideas by finding out if the oceans cooled at the time the East Antarctic ice sheet first formed. Temperature records will be constructed using measurements of the Mg/Ca ratios of foraminifera from ancient seafloor sediments recovered by the Tanzania Drilling Project